"My Settings" menu link is wrong in 2 out of our 3 environments

In our production and UAT environments, the "My Settings" page throws a 404. This is the dropdown menu link from the upper right corner of Edit/Admin mode.

I went snooping around and found that the link is just wrong. On our local environments, the "My Setttings" menu option goes to:

/admin/CMS/edit/mysettings.aspx

This works fine. And when I manually paste that URL into production and UAT, it works fine there too.

However, the "My Settings" menu option from production and UAT goes here:

/admin/Shell/Settings

This throws a 404. Why would the menu link be different between the environments? I've looked around and can't find a single setting for changing this value. Is this set somewhere in particular?

(The Dashboard on production/UAT throws a 404 too, but it doesn't locally. I suspect these two problems are related.)

(One possible source of weirdness. Our local environments for this particular client are 32-bit. The production/UAT environments are 64-bit. Which means that locally, EPiServer is in "Program Files" and in production/UAT it's in "Program Files (x64)". I'm wondering if somewhere out in a config file in production/UAT, there's a path set to just "Program Files." However, I cannot find this anywhere. Where should I look next?)